The limited availability of arable land and the declining soilfertility have led to an increasing application of chemical fertilizers to respond to the increasing demand for more food by the growing population. Micronutrients are essential for plant growth, albeit in small amounts. However, these elements are rarely present in some of the calcareous soils across the world, or in those with an alkaline pH, a low organic matter content (i.e., the conditions of most soils in Iran), or a coarse texture. Researchers have been directing their efforts on enhancing micronutrient utilization efficiency by using new technologies to reduce fertilizer application and to decrease, there by, farm costs and environmental pollution. Along these lines, nanotechnology has been successfully exploited to produce nanofertilizers (materials typically smaller than 100 nm at least in one dimension)for plant nutrition, mostlyin greenhouse, and in vitro applications. The positive effects of nano-fertilizers of iron, zinc, manganese, copper, and molybdenum as a new generation of fertilizers have been reported on the growth indices of wheat, canola, sorghum, beans, cucumbers, tomatoes, peanuts, and some medicinal plants, among others. Despite all this, there is no shortage of reports on lack of or negative effects of nano-fertilizers. Moreover, there is only scant knowledge presently available on the likely consequences of introducing large amounts of these substances into the environment and the food chain. Thus, production of safe and useful nanofertilizers seems to await more in-depth research.

FAO (Food and Agriculture Organization of the United Nations) (2009) How to feed the world in 2050. Proceedings of the Expert Meeting on How to Feed the World in 2050. 24–26 June 2009. FAO Headquarters, Rome.